Let's get this math done. We have 872 and we're going to multiply it by 25. This is the same as taking 872 and adding it to itself 25 times.
Step 1: 0 + 872 = 872
Step 2: 872 + 872 = 1744
Step 3: 1744 + 872 = 2616
Step 4: 2616 + 872 = 3488
Step 5: 3488 + 872 = 4360
Step 6: 4360 + 872 = 5232
Step 7: 5232 + 872 = 6104
Step 8: 6104 + 872 = 6976
Step 9: 6976 + 872 = 7848
Step 10: 7848 + 872 = 8720
Step 11: 8720 + 872 = 9592
Step 12: 9592 + 872 = 10464
Step 13: 10464 + 872 = 11336
Step 14: 11336 + 872 = 12208
Step 15: 12208 + 872 = 13080
Step 16: 13080 + 872 = 13952
Step 17: 13952 + 872 = 14824
Step 18: 14824 + 872 = 15696
Step 19: 15696 + 872 = 16568
Step 20: 16568 + 872 = 17440
Step 21: 17440 + 872 = 18312
Step 22: 18312 + 872 = 19184
Step 23: 19184 + 872 = 20056
Step 24: 20056 + 872 = 20928
Step 25: 20928 + 872 = 21800

So, 872*25 = 21800